Pneumatic tires for highway service are subjected to severe stresses from the heavy loads, high driving and braking torque, cornering forces, and high speed flexing, which occur in present day operation. Even the most modern tire building equipment does not always place the internal elements with the intended degree of uniformity, and the final molding operation hides non-uniform placement which can lead to stress concentration and consequent premature failure, so that external inspection is not adequate for separating good tires from bad ones.
The most successful procedure for locating defects in internal placement of elements of pneumatic tires is X-ray inspection, but in spite of many recent advances, it has continued to be so slow and expensive that routine inspection of every tire has added significantly to cost and therefore to sales price.
An object of this invention accordingly is to automate the operation of an X-ray inspection machine, so that it will require a minimum of attention and therefore a minimum labor cost.
Another object is to make an X-ray inspection machine of maximum versatility so that it can handle random mixes of types and sizes as they appear in production operations without requiring any expensive presorting. Still another object is to provide equipment which will accept the smallest highway tires in spite of the difficult geometrical problems of fitting into a small bead circle an X-ray tube of irreducible size because of the need for very high voltage insulation, and bead spreading mechanism of adequate size and strength so that it will also separate the large and stiff beads of large highway truck tires.
A further object is to provide a machine which can be used optionally for 100% visual inspection or for automated examination for specific conditions, or for both together or sequentially.